FR2460019A1 - ARRAY CONTROL DEVICE IN LINEAR DISPLACEMENT READ HEADING APPARATUS - Google Patents

Abstract

A. ARM CONTROL DEVICE IN A LINEAR DISPLACEMENT READING HEAD APPARATUS, DEVICE INCLUDING GUIDING MEANS 18, 19, A TROLLEY 14 SLIDING ON THESE GUIDING MEANS, A DRIVING MOTOR 28 TO DRIVE THIS TROLLEY ACCORDING TO A LONGITUDINAL DIRECTION OF THESE GUIDING MEANS AND A READING HEAD ASSEMBLY 5 MOUNTED ON THIS TROLLEY BEING LIKELY TO MOVE AND INCLUDING A SUPPORT MECHANISM 6, 7, 12, 13 FOR SUPPORTING AN ARM INTENDED TO MOVE HORIZONTALLY TO A DISC. B. DEVICE CHARACTERIZED IN THAT IT INCLUDES IN ADDITION MEANS 105, 79, 86, 87 TO GENERATE AN EXIT SIGNAL IN RESPONSE TO A TILT OF THE TROLLEY, AS WELL AS MEANS 106, 88, 89, 90 TO APPLY THIS SIGNAL EXIT TO THE DRIVE MOTOR SO AS TO STOP THE TROLLEY IN A PREDETERMINED POSITION WHEN THE ARM IS AWAY FROM THE DISC. C. THE INVENTION APPLIES IN PARTICULAR TO STEREO REPRODUCTION.

Description

le 2 4 2460019

  The present invention relates to a device

  to control an arm in a linear displacement read head apparatus which is used for

  sound or video recording reproduction from a disc

  than phonograph or video disc. As a read head device or read head apparatus completely eliminating lateral displacement error and internal forces, it has been proposed

  and put into practice a device or apparatus of head of read-

ture said to linear displacement.

  In some linear displacement type recording reproducers, a screw-type control mechanism

  a target are used to linearly control the arm.

  However, as the precision of realization of the mechanism of com-

  Mande by screw and cable are not very high, the arm can not be moved gently. In addition, a breeder has been proposed where an arm is driven along rails by a

  linear motor. When the power supply is disconnected

  the linear motor, the arm can be moved freely since there is no force to hold it. Generally the arm is supported by a carriage and the arm is moved at the same time as the carriage. the weight of the moving part is of considerable importance. When the reproducing apparatus is inclined with respect to the horizontal plane, the arm and the carriage

  are displaced due to gravity. When the apparatus of

  production is supported on its base by a flexible support,

  there is a risk that the device will be tilted with

arm cement.

  During disc reproduction, when the arm is unexpectedly displaced by motor vibration or ground vibration, the reproduced output signal is modulated and crosstalk between the R and X signals is increased in the stereo reproduction. If the frequency of the vibration is close to the resonance frequency of the arm or coincides with

  these phenomena take on a remarkable scale.

  In the reproduction and recording apparatus

  In the linear displacement type, the arm is rotated by the groove of the disk and thus angularly displaced in a direction perpendicular to this groove. If the angular displacement of the arm reaches a predetermined value, the arm is

2.- 2460019

  then entered linearly so as to suppress the angular displacement. Thus the rotation of the arm and the linear displacement

  of this arm are repeated alternately. the arm moves

  only by oscillating around its axis. When the oscilla-

  If the signal is too intermittent, the signals can not be reproduced faithfully. It is desirable that the repetition of the rotational-linear movement of the arm is really fine and

  frequent and the arm is moved gently.

  When a counter weight is used to adjust the pressure of the transducer on the disk, the axis of rotation of the

  arm should not coincide with the center of gravity of that

  this. Some torque is applied to the arm with the linear displacement of this arm. Some angular displacement is added to the actual angular displacement. Linear displacement

arm becomes unstable.

  Further, in the linear displacement type reproducing apparatus, the arm is rotatably supported on a carriage which is linearly displaced. In such an arrangement, the rotation of the arm relative to the carriage must be braked for example by a reaction control of the movement, to move the arm gently and linearly. A rotation detector and a drive motor are provided for the motion feedback control. When mounted

  on the trolley, a large space is necessary in the direction

  longitudinal direction of the axis of rotation of the arm. adjustment

in arm level is limited.

  Accordingly, the general purpose of the invention

  is to create an arm control device for a device

  linear movement arm which eliminates the

  of the prior art described above. Another goal of the

  The purpose of this invention is to create an arm control device for a linear motion arm apparatus by which the arm

  can be moved gently to a disc.

  Another object of the invention is to create an arm control device for an arm

  linear motion in which the arm can be moved

  on a disk by a linear motor while

  The reaction yens are intended to prevent irregular movement

tie this arm.

  Another object of the invention is to provide an arm control device for a linear motion arm apparatus in which the arm is driven by a linear motor, while means are provided for pocketing.

  unnecessary movement of the arm, even when the

  duction is not perfectly horizontal. Another object of the invention is to create an arm control device for an arm

  linear displacement in which control means in response to

  movement are provided to avoid the adverse influence of

  ble on the reproduction of the disc of undesirable vibrations

  undergone by the arm traversing the disc.

  Another object of the invention is to create an arm control device for a linear motion arm apparatus in which detection means are provided for detecting movement of the arm driven by a linear motor, means for applying in return the output

  detection means to a motor control circuit li-

  other detection means being provided for detecting the offset angle of the arm and other means for applying

  the output of these other detection means to the communication circuit

  command of the linear motor thanks to which the arm can be moved

  gently while playing the disc.

  Another object of the invention is to create an arm control device for a linear motion arm apparatus in which a low vibration of the arm in the horizontal direction or in the vertical direction

  or weak Vibration of the arm in the horizontal directions

  Zontal and vertical are detected during the reproduction of the disk, the output thus detected being applied to a horizontal drive motor or to a vertical drive motor, or the outputs thus detected being applied to the horizontal drive motor and to the drive. vertical drive motor, thanks to which we can remove the vibrations of the arm

  and obtain a high quality reproduction.

  Another object of the invention is to create an arm control device for an arm

  linear motion, in which the arm is supported by the

  of a carriage on a pair of guide rails, while a horizontally rotating drive motor and a horizontal rotation detector for the arm are arranged

4 2460019

  between the guide rails, which translates into dimensions

  reduced reproduction apparatus.

  Another object of the invention is finally to create an arm control device for a linear motion arm apparatus in which a displaced arm is provided.

  linearly in the horizontal direction by a linear motor.

  re, detection means for detecting the offset angle

  arm, a circuit for applying the output of the means of de-

  tection through a first switch to a cir-

  fired control of the linear motor, a detection circuit for detecting the inclination of the reproducing apparatus, and

  another circuit to apply the output of this circuit of de-

  through a second switch to the linear motor control circuit, the first switch being

  closed for a downward movement of the arm, while the

  cond switch is closed for upward movement of the arm, thus improving the quality of movement of the arm

  and undesirable vibration of this arm is thus avoided.

  To achieve these aims, the invention relates to an arm control device in a linear displacement reading head apparatus, device comprising guide means, a carriage slidably mounted on these guide means, a drive motor for driving, this carriage in a longitudinal direction of these guide means and

  a set of read head mounted on this carriage being sus-

  movable with a support mechanism for supporting an arm intended to move horizontally with respect to a disc, characterized in that it comprises,

  in addition, means for generating an output signal in response to

  to the inclination of the trolley, as well as the means for

  send this output signal to the drive motor in order to

  Reattach the carriage to a predetermined position when the arm

is away from the disc.

  The invention will be explained in more detail

  with reference to exemplary embodiments shown in the accompanying drawings in which: - Figure 1 is a plan view of a reproduction apparatus equipped with a read head apparatus to

  linear displacement, in accordance with an embodiment of the invention

  FIG. 2 is a perspective view of an arm control device in the linear displacement reading head apparatus of FIG. 1; FIG. 3 is a cross-section on a larger scale along the length of FIG. of line III-III of FIG. 2, FIG. 4 is an enlarged cross-section along line IVIV of FIG. 2, FIG. 5 is a perspective view on a larger scale of a detector. in FIG. 1 is a side view of the detector of FIG. 5, FIG. 7 is a perspective view of a substantial part of the mechanism for detecting the free movement of a carriage in the apparatus of Fig. 1; - Fig. 8 is a block diagram of a linear motion control reaction circuit for the arm of Fig. 1; - Fig. 9 is a diagram. in blocks of a motion reaction circuit for the vertical rotation of the arm, FIG. 10 is a block diagram of a motion reaction circuit for the horizontal rotation of the arm,

  FIG. 11A is a graph of the characteristic

  low resonance frequency tick of a conventional arm,

  FIG. 11B is a graph of the characteristic

  low resonance frequency of the arm according to the in-

  vention. FIG. 12 is a block diagram of a circuit for pocketing the free movement of the arm,

  FIG. 13A is a front view of a

  that split in the apparatus of Figure 1,

  FIG. 13B is a waveform of the

  of a light-sensitive element in the equipment of Figure 1, 9

  FIG. 130 is a waveform of a

  of an operational amplifier to which the

  of the light-sensitive element shown in Fig. 13B, Fig. 14 is a representation for

  large scale of a portion of the waveform of Figure 130.

  FIG. 15A is a schematic side view

  that of a significant part of the production apparatus which is placed at an angle inclined upwards to the right of the horizontal plane,

  FIG. 15B is a schematic side view

  that a substantial part of the production apparatus which is inclined upwards to the left of the horizontal plane; - Figure 16 is a block diagram of a modification of the circuit intended to prevent free movement;

of the arm.

  We will now describe an achievement of

  the invention with reference to the drawings.

  Fig. 1 is a plan view of a reproduction apparatus equipped with a linear displacement pickup head apparatus according to an embodiment of the present invention. Referring to this Figure 1, a large circular opening 2 is formed in an upper plate of the box of the reproduction apparatus. A record player is disposed in the opening 2 being supported so as to be rotatable by a pivot 4. An arm 5 is disposed above the

  top plate 1 of the cabinet and attached to a parallel cabinet

  The casing 6 is connected to a horizontal control arm

  7. The horizontal control arm 7 is designed to

  ability to move linearly to the left and right (Figure 1).

  As a result, the arm 5 moves in a sound groove of a recording disk 8, always maintained in the tangential direction at this sound groove of the disk.

  8, so that a transducer 9 fixed at the end

  arm 5 runs linearly through the recording disk

  8. A rear arm 10 aligned with the arm 5 is attached to the

  back king of the box 6. A counterweight 11 is attached to the arm

rear 10.

  We will now describe the mechanism for linearly moving the arm 5 with reference to the figures

2 to 4.

  The horizontal control arm 7 is inserted vertically into a sleeve 12 as shown in particular in FIG. 3, and is rotatably supported by 6.- 7.-

  two ball bearings 13 which are arranged at the upper end

  re and at the lower end of the sleeve 12. the sleeve 12 pas-

  through a hole 16 punched in a boss 15 of a chain.

  The sleeve 12 is fixed to the boss 15 by a locking screw 17 as shown in FIG. 4. When the screw 17 is loosened, the sleeve 12 can be moved in the direction

  vertical. As a result, the level of the arm 5 can be adjusted.

  The carriage 14 supporting the horizontal control shaft 7 is itself supported by a pair of rails 18 and

  19 to slide along these rails. To this effect

  fet a pair of support plates 20 and a block of supports

  21 are attached to the lower surface of the carriage 14. the

  20 supports are separated from each other in the direc-

  longitudinal sliding of the rail 18. Sliding bearings 22 are held in the support plates 20 respectively. The rail

  18 is adjusted in sliding bearings 22. A recess

  23 is formed in the support block 21. The rail 19 passes

  through this recess 23. A roller 24 is supported by the

  a support pin 25 through the support block

  21, so as to be in contact with the rail 19. Thus, the chain

  riot 14 is supported at three points of rails 18 and 19 by the

  intermediate of the sliding bearing pair 22 and the roller 24.

  The rails 18 and 19 are supported at their ends by U-shaped support members 26 and 27, as shown in FIG.

figure 2.

  Under the rail 18 a linear motor 28 is dis-

  placed parallel to the rail 18, as shown in Figure 3. the linear motor 28 comprises a pair of permanent magnets 29 parallel to each other and a coil 30 which is arranged

  in a magnetic circuit including permanent magnets 29.

  the permanent magnets 29 are fixed by way of

  mounting members 31 to the support members 26 and 27. The

  Mounting plates 31 are magnetically coupled with the permanent magnets 29 and play the cylinder head. The spool 30 is wound on a spool support 32. Upward protrusions 33 are formed on the spool support 32 and are attached to the support plates 20e A bolt 35 passes through a hole

  34 of the coil support 32 and is supported by its

  tremities by the support plates 26 and 27. The magnetic circuit

  The tick is formed by the mounting plates 31 and the bolt 35.

  8. When a current passes through the coil 30, a force in

  the longitudinal direction of the rail 18 is applied to this

  This force is transmitted through the

  33 of the coil support 32 and the support plates 20 to the carriage 14. Thus, the carriage 14 is moved along the

rails 18 and 19.

  Under the rail 19, a linear displacement detector 36 is arranged parallel to the rail 19. The linear displacement detector 36 consists of a single permanent magnet 37, mounting plates 39 'acting as a cylinder head and a cylinder head 43 magnetically coupled with the magnet 37 to form a magnetic circuit, a coil 38 being arranged

  in this magnetic circuit. The magnet 37 is supported by the

  of the mounting plates 39 by the support members

  port 26 and 27 (see Figure 2). The coil 38 is wound on

  a coil support 40 as shown in FIG.

  41 upwardly formed on the coil carrier 40 is

  The bolt 43 passes through a central hole of the spool support 40 and is supported at its ends by the support members 26 and 27. the spool

  38 is moved at the same time as the carriage 14. the magnetic flux

  tick from the magnet 37 interferes with the voice coil.

  38. As a result, a current flows through the coil 38.

  The linear motor 28 and the displacement detector

  linear elements 36 are arranged separately from one another under the rails 18 and 19. Consequently, the flow of loss in

  from the linear motor 28 has no influence on the

  In addition, the noise coming from the linear motor 28 is not detected by the detector 36. As will be described hereinafter, a motion reaction is performed by the detector 36. The arm 5 can be

  moved really gently in the horizontal direction.

  We will now describe the mechanism

  both to vertically control the arm 5 and a detector

of vertical displacement.

  The upper end of the horizontal control shaft 7 is fixed on the bottom of a U-shaped connection member 44, as shown in FIG. 4. A horizontal shaft

  is mounted on the connection member 44. the arm 5 is driven by

  born vertically around the horizontal shaft 45. the two 9.terminal parts of the horizontal arm 45 pass through the walls

  side of the casing 6o The casing 6 and the arm 5 fixed to the bowl-

  tier 6 are supported so that they can be rotated through

  of the horizontal shaft 45 by the horizontal control shaft

  7. The arm 5 is likely to turn around the tree

  horizontal 45 so as to come into contact with the drive disc

  registration 8 and to be able to be separated

  As shown in Figure 3, the driving motor

  vertically 46 and a vertical displacement sensor 47

  are arranged inside the casing 6. The driving motor

  vertical direction 46 is disposed on the side of the arm relative to the axis of the horizontal drive shaft 7. The motor 46 is constituted by a pair of permanent magnets 48 (FIG. 2), a part of the 6 and a magnetically coupled cylinder head 52 and respectively with the permanent magnets 48 to form a magnetic circuit, while a coil 49 is disposed in this magnetic circuit magnets 48 are fixed on the walls

  The stacker 6 plays the role of the breech.

  The spool 49 is wound on a square spool support 50 which is attached to the connecting member 44. The bolt 52 passes through a central hole 51 of the spool support 50 and is attached to the casing 6. The upper end the cylinder head 52 is

  in contact with a cover 53 of the casing 6.

  The vertical displacement detector 47 is

  in the same way as the vertical drive motor.

  cal 46. It consists of a pair of permanent magnets 54, in

  part of the bottler 6 and a cylinder head 58 coupled magnetic-

  respectively with the permanent magnets 54 for

  kill a magnetic circuit in which is disposed a coil 56. The magnets 54 are attached to the opposite side walls of the casing 6. The coil 56 wound on a coil carrier 55 is disposed between the magnets 54. The coil support 55 is fixed to the connection member 44. The yoke 58 passes through a central hole 57 of the coil support 55 and is fixed on the

  6. The upper end of the cylinder head 58 is in

  tapt with the cover 53. When a current flows through

  coil 49, a force is applied to the magnets 48 and

  block 6 and arm 5 to rotate them

  turn of the horizontal axis 45o A current passes through the coil 56 of the detector 47 during the vertical movement of the arm 5 or

  during a vertical vibration of this arm 5. As a result,

  vertical direction or the vertical movement of the arm 5 is detected

  by the detector 47. When the output thus detected from the detector

  47 is sent back to the motor 46, the arm 5 is prevented from vibrating during its upward and downward movements.

down and during breeding.

  We will now describe a driving motor

  horizontally and a horizontal displacement detector

  placed on the sides of the lower part of the drive shaft.

horizontally 7.

  As can be seen clearly in Figure 4, a

  connection plate 59 is attached to the horizontal drive shaft.

  7. Coil carriers 60 and 61 are attached to this connecting plate 59. The coils 62 and 63 are wound on the coil carriers 60 and 61 respectively. Two permanent magnets 64 are disposed above and below the coil 62. Two other permanent magnets 65 are disposed below the coil 63. The magnets 64 and 65 are fixed on the inner walls of a casing 66 which is attached to the sleeve 12. The shoemaker

  66 plays the breech, breeches 67 and 68 go through

  towards central holes 69 and 70 of the coil supports 60 and

  61 and are attached to the side wall of the casing 66.

  A horizontal drive motor 71 consists of magnets 65, yokes 66 and 68 to form a magnetic circuit and a coil 63 is disposed in this magnetic circuit. A horizontal displacement detector 72 includes the magnets 64, the yokes 66 and 67 to constitute

  a magnetic circuit and the coil 62 is arranged in this circuit.

  magnetic cooked. When the arm 5 vibrates in the horizontal direction

  and during the reproduction of the disc, the coil 62

  rolled on the spool support 60 moves around the horizontal drive shaft 7. Since the spool 62 is disposed

  between the magnets 64 a current passes through this coil 62.

  As a result, the horizontal vibration of the arm 5 is detected by the detector 72. The thus detected output of the detector 72 is applied back to the coil 63 of the motor 71. A current

  passes through the coil 63. A force is applied to the

  coil port 61 on which is wound coil 63 and she

  is transmitted by the connection plate 59 and the drive shaft

  o. 11 is horizontal 7 at arm 5, This force is opposed to the force of vibration. Thus, the horizontal vibration of the arm 5 is pocketed. the horizontal drive motor 71 and the horizontal displacement sensor 72 are arranged between the

  horizontal linear drive motor 28 and the detector

  linear displacement. 36. Consequently, an additional space

  re is not necessary for the horizontal drive motor 71 and the horizontal displacement sensor 72. The level of the

  arm 5 can be adjusted to a considerable extent.

  the locking screw 17, the casing 66 containing the motor 71

  and the detector 72 can be moved sufficiently in the di-

  vertical rection between the rails 18 and 19 at the same time as the sleeve 12, the center of gravity of all the parts attached to the carriage 14 is located midway between the rails 18 and 19 and inside the triangle formed by connecting the three

  points on which the carriage 14 is supported by the intermediate

  The sliding bearings 22 (see Figure 3) and the roller 24 on the rails 18 and 19, RE, the carriage 14 can be moved very gently in the horizontal direction. In addition,

  no undesirable effort is applied to rails 18 and 19.

  We will now describe a switchgear

  offset angle detection with reference to FIGS. 4 to 6.

  A support plate 73 is attached to the end

  lower part of the horizontal drive shaft 7. A flap 74 is attached to the end of the support plate 73. Another

* support plate 75 is fixed to the bottom of the casing 66. The end

  This second support plate 75 is folded into a U shape. Two light-sensitive elements 76 and 77 are attached to the upper part of the U-shaped end of the support plate 75. A light emitting element 78 is attached to the lower part of the U-shaped end of the plate

  75. The flap 74 is disposed between the sensing elements

  lights 76 and 77 and the light emitting element 78.

  When the horizontal drive shaft 7 rotates, the flap 74 moves relative to the light emitting element 78 and the light-sensitive elements 76 and 77 to change the

  amount of light received on light-sensitive

  re 76 and 77. Thus, the offset angle of the drive shaft

24 60 0 19

2.2460019

horizontal 7 is detected0

  We will now describe a mechanism to de-

  the movement of the carriage 14 due to gravity when the application

  similar reproduction is inclined. As shown in FIG. 3, a slotted plate 79 is arranged parallel to the rail 19. This

  the slotted plate 79 is attached at both ends through

  arm 81 to a frame 80 held by the holding members 26 and 27, the slotted plate 79 is made of an opaque material. As shown in FIG. 79, a number of slots 82 are provided at regular intervals on slotted plate 79. A side arm 83 forms an integral part of carriage 14, as shown in FIG. 3. Two projections 84 and 85 downward are provided on the lateral arm 83, a transmitter element of

  light 86 is fixed on one of the projections down 84.

  A light-sensitive element 86 is attached to the other projection

  85, the slotted plate 79 is arranged between

  the light-emitting element 86 and the light-sensitive element

  As a result, when the carriage 14 is moved along the rails 18 and 19 due to gravity, the light emitting element 86 and the light-sensitive element 87

  move relative to the slotted plate 79. A warning signal

  sinusoidal tie is generated from the sensitive element-to

the light 87.

  We will now describe the operation of

  the reproduction apparatus in automatic reproduction.

  At the start of automatic playback,

  arm 5 is in its rest position, as shown in FIG.

  Figure 1. The linear motor 28 is supplied with energy by an actuator, not shown, or by instructions from a control system, not shown. The arm 5 is moved linearly to the left

(figure 1).

  In FIGS. 2 and 3, a current flows through

  to the coil 30, a driving force is applied to the linear motor 28, The carriage 14 is moved along the rails 18 and 19 by the driving force of the linear motor 28. The arm 5 is supported via the box 6 of the tree

  horizontal drive 7 and the sleeve 12 by the carriage 14.

  As a result, the arm 5 is moved linearly in a di-

  perpendicular to the longitudinal direction of this arm 5.

1 20-

  The motion control by reaction is effected

  for the linear motor 28 by the linear displacement sensor 36 (see FIGS. 2 and 3), Accordingly, the arm 5 is moved slowly, as shown in FIG. 8, the detection output voltage of the coil 38 of the detector of displacement

  linear waveform 36 is applied to an input terminal of an ampli-

  88. A voltage applied to the coil 30 of the

  linear motor 28 is applied back to the other terminal of

  of this operational amplifier 88. Thus, the two

  are compared to each other in the op-

  88. The impedance of transistors 89 and 90 varies with the importance of the output of operational amplifier 88, to change the intensity of the current flowing in the coil.

training 30.

  When the impedance of the transistor 89 is low, the intensity of the current flowing through the drive coil 30 is important. The arm 5 is moved at a high speed. In such a case, the arm 5 tends to exceed a desired location

  of the disk 8, it is difficult to stop the arm 5 in the posi-

  desired, however, in accordance with the achievement of the

  vention, the output of the coil 38 is applied to the first input terminal of the operational amplifier 88 and it depends

  the speed of movement of the brass5 or the carriage 14.] n

  sequence the impedance of the transistor 89 cro t with the speed of movement of the arm 5. As a result, the current flowing through the coil 30 is reduced, and the arm 5 is moved to the position

  of the disc 8 from its rest position to a

predetermined speed.

  In the introduction operation, the arm 5 is brought into a recording position of the disc 8 from the rest position, and in the output position o the arm 5

  is brought to its rest position from a position of

  recording of disk 8, a bias voltage for

  the conduction of transistors 89 and 90 is applied, although not shown, to the input terminal of the operational amplifier. By a recording size detector, Gu detects that the transducer 9 carried by the arm 5 reaches

   the outermost recording groove of the recording disc.

  FIG. 80 The bias DC voltage is cut off from the operational amplifier 88 to stop the linear motor 28. Although not shown, the arm 5 is moved.

  down by instruction from the system control. A neck-

  rant passes through the coil 49 of the vertical displacement motor

  46 as shown in Figures 2 and 3. The engine of -

  vertical displacement 46 is controlled to rotate the bot-

  tier 6 supporting the elements 48 and the cylinder head 52 of the motor 46 around the horizontal shaft 45 in the counterclockwise direction, (Figure 3). As a result, the arm 5 is rotated in the counter-clockwise direction to bring the transducer 9 into contact with the recording disk 8. The reproduction of the recording starts.

  In the vertical rotation of the arm 5, a conm-

  motion response is applied to the detector of

  vertical rotation 47 so as to maintain the exit of the

  speed detection sensor of the vertical rotation detector

  47 by a circuit of FIG. 9. Thus, the arm 5 can

  be rotated very gently in the vertical direction

  down. The circuit of FIG. 9 is constituted in much the same way as the control circuit of the linear motor 28,

  shown in Figure 8, it includes an operational amplifier

  91 to compare the voltage applied to the coil 49 of the motor 46 with the output voltage of the sense coil 56, and two transistors 92 and 93 whose impedances vary with the output of the operational amplifier 91.

  arm 5 is entralné down and up, when starting

  rage of the reproduction of the recording and at the end

  of this reproduction, a continuous polarization voltage of

  to selectively turn transistors 92 and 93 into

  driver's state and in the non-conductive state, is applied, although

  not shown, at the input terminal of the amplifier

rational 91.

  We will now describe the movement of the arm 5

  during the reproduction of the recording.

  The sound groove is formed in spirals on the recording disk 8. The transducer attached to the arm 5

  is gradually moved to the center of the recording disc.

  8 when this recording disk 8 rotates. The arm 5 rotates gradually in the direction of clockwise

15.- 22460019

  (Figure - 1) around the horizontal drive shaft 7. As a result, the holding plate 73 connected via the casing 6 and the horizontal drive shaft 7 to the arm, rotates gradually in the same direction, the flap 74 attached to the end of the holding plate 73 is moved into

  the radial direction of the recording disk 8 and it is de-

  placed with respect to the light element 78 and the sensing elements

  in light 76 and 77. the quantities of light received -

  by the two light-sensitive elements 76 and 77 differs

  meet each other. The difference between the amounts of light received by the light-sensitive elements 76 and 77 is detected by an operational amplifier 94, as shown in FIG.

  shows the figure 8o the output of this operational amplifier-

  94 is applied via a circuit 101 to a first

  Accordingly, the impedance of the transistor 89 is lowered by the output of the operational amplifier 88 and a current flows through the coil 30 of the motor 28, hence the linear motor 28. is driven and the arm 5 is moved towards the center of the disc

  8 by means of the carriage 14 by means of the

linear transmitter 28.

  In the recording reproduction according to

  the embodiment of the invention, the arm 5 is displaced angular-

  when the recording disk 8 rotates. This angular displacement or this offset angle of the arm 5 is detected by

  the light-sensitive elements 76 and 77. Thanks to this

  tection, the linear motor 28 is controlled to move the

  carriage 14 so as to eliminate the offset angle of the arm 5.

  Thus, the arm 5 moves linearly by oscillating around

  horizontal drive shaft 7.

  the polarization voltage corresponding to the year

  arm offset 5 is applied to a first bound

  input of the operational amplifier 88 of the communication circuit

  control of the linear motor 28 added to the detection output

  the coil 38. Thus, the linear motor 28 is controlled

  to remove the offset angle of the arm 5 by being czm-

  moved by reaction on the basis of the detection of

  the coil 38. The offset angle error is very small.

  The arm 5 can be moved very finely, very gently and

  linearly, oscillating finely around the tree of

16.- 24600 1 9

  7. The circuit to remove the angle of

  arm offset 5 and the control circuit for the motor

  28, have common parts, Consequently, the

  truction of these circuits is simplified.

  The reaction motion control is effected also for the horizontal rotation of the arm 5 by the horizontally rotating drive motor 71 and the horizontal rotation detector 72 shown in FIG. 4,

  in order to pocket the arm 5 to vibrate in the horizontal direction.

  Generally, there is no provision for

  braking on the arm except bearing friction.

  As a result, the arm tends to vibrate in resonance, or it tends to vibrate under the action of an external force although this vibration is very weak. When the arm 5

  vibrates in the horizontal direction, crosstalk increases

  the R and L signals in the stereo reproduction or the reproduced output is modulated, In addition, the center of gravity of the arm 5 is placed before the vertical drive shaft 7 as shown in the reference number 95 in the figure 1. Accordingly, when the arm 5 is moved in the horizontal direction, a force is applied to the arm 5 so as to oscillate it around the center of gravity 95.

  component different from the current offset angle is detected.

  The horizontal entrapment of the arm 5 would become very unstable.

  However, in accordance with this

  the detection output of the coil 62 of the detector 72 and the voltage applied to the coil 63 of the drive motor

  horizontal 71, are compared with each other by the amplification

  As shown in FIGS. 4 and 10, the present invention can be used to selectively control both transistors 97 and 98. As a result, a current flows in the control coil 63 in the normal or reverse direction. A driving force is generated in the motor 71 so as to make the output of the coil of

  detection 62 void. The rotation of the arm 5 around the shaft of

  horizontally 7 is controlled by the training force

  The arm 5 can be moved gently in the direction

  horizontal with high precision and without fluctuation.

  When the arm 5 is vibrated in the horizontal direction, a voltage corresponding to this vibration and the direction thereof is generated in the

17.- 2460019

  coil 62. This voltage selectively turns transistors 97 and 98 into the conductive state and the non-conductive state. As a result, a current flows through the coil 63 from the + B terminal to ground, or from the ground to the - B terminal. Thus, the motor 71 is driven to pock

the vibration of the arm 5.

  Thanks to the motion control by reaction of the horizontal rotation of the arm 5, the horizontal vibration

  of this arm 5 is reduced. Intercom is reduced to a minimum of

  mum. As shown in FIG. 11A, when the motion control

  reaction is not performed in the horizontal rotation.

  In the zone of the arm 5, the output of the transducer takes a peak shape at the low resonance frequency f0 and the crosstalk between the signals R and X $ 'increases with the frequency of msonnance.

  bass in stereo reproduction.

  However, in accordance with the movement command

  reaction of the present embodiment, the output of the trans-

  Distortion and crosstalk take a flattened form also at the low resonance frequency fo as shown in Figure 11B. In addition, the modulation of the reproduced output signal is

  suppressed by braking the vibration of the arm 5.

  During reproduction, the arm 5 is vibrated in the vertical direction by the warping of the disk

  in rotation or by an external vibration. A corresponding voltage

  the direction and amplitude of this ver-

  the armature 5 is generated in the coil 55 of the vertical rotation detector 47. As shown in FIG. 9, this voltage is applied to an operational amplifier 91 for

  selectively make conductive and non-conductive

  As a result, a current flows through the motor coil 46 from the + B terminal of the voltage source to ground, or from ground to the B terminal of the voltage source. Thus, the motor 46 is controlled so

  to pocket the vibration of the arm 5. The arm 5 is brought to the con-

  tact of the disc always at a predetermined pressure. Thus, the reproduced output signal can always be obtained with

high fidelity.

  We will now describe how to prevent

  linear movement of the arm 5 in the case where the reproduc-

  registration is stopped during the journey.

18.- 2460019

  During a reproduction or at the end of a reproduction, the vertical rotation drive motor 46 is controlled by instructions of an operating apparatus,

  not shown, so that the arm 5 is driven in -

  rotation about the horizontal shaft 45 in the direction of the needles of a watch (FIG. 3) to separate the transducer from the

  disc 8 and to stop playback of the recording.

  The upward movement of the arm 5 is detected by two organizations

  detection numbers 99 and 100, shown in FIG.

  For example, the first detection member 99 is constituted by

  one permanent magnet and the other detection member 100 is con-

staggered by a Hall element.

  When moving up the arm 5

  is detected by the Hall element 100, the electronic switch

  101 is open, while another electronic switch 102 is closed in the block diagram of FIG. 12. As a result, the output of an offset angle detector 103 is cut off from a position servocircuit 104, while the

  the output of a position detector 105 is applied to the servo

  position circuit 104. Thus, the linear drive motor

  horizontally 28 generates a training force to em-

  fishing the free movement of the arm 5. The angle sensor of

  offset 103 is constituted by the flap 74, the sensory elements

  light 76 and 77, and the light emitting element 78.

  The position detector 105 is constituted by the slotted plate 79, the light emitting element 86 and the light-sensitive element 87. The detail of the position servo-circuit 104 is

shown in Figure 8.

  the reason the linear motor of

  horizontal translation 28 is controlled when the arm 5 is disengaged

  Upward position is as follows: The linear displacement arm 5 controlled by the linear motor 28 is freely moved along the rails

  18 and 19 when the reproductive apparatus is tilted

  port to the horizontal plane. When the reproductive device is

  supported by a flexible support member, this apparatus has

  dance to bow with the movement of the arm 5, since the

  arm 5 with the carriage 14 represents a significant weight.

  When the arm 5 moves freely, the element

  light emitter 86 and the light-sensitive element 87

21496.0-0 619

  fixed on the carriage 14 move relative to the slotted plate 79 (see Figures 2 and 7). As shown in FIG. 13A, slots 82 are provided at regular intervals on slotted plate 79. The output shown in FIG. 133 is obtained from light-sensitive element 87. This output is amplified by an amplifier. 106 and

  it is compared with a reference voltage given by a-

  variable resistor 107. A sinusoidal output as shown

  Figure 13C is obtained from the operational amplifier.

  rational and is applied to a first input terminal of the operational amplifier 88 shown in FIG. 8,

  by being added to the output of the coil 38.

  As shown in Fig. 14, when the light-sensitive element 87 aligns exactly with the slot 82, the output of the operational amplifier 106 reaches a positive maximum. When the light-sensitive element 87 is shifted

  of a half pitch of slots 82 of the slot 82, the output of the amplifier

  Operational indicator 106 takes a negative maximum. When the light-sensitive element 87 is shifted by a quarter of a step

  slots 82 of the slot 82, the output of the amplifier

  tional 106 becomes zero, this voltage is applied to the cir-

  fired displacement reaction of the linear motor 28 represents

  Figure 8. The driving force of the linear motor

  Corresponding to this tension is balanced with the

  the weight of the carriage 14 and the parts associated therewith

  in the longitudinal direction of rails 18 and 19.

  When the reproduction device is placed

  horizontally, the arm 5 is balanced aurpointsa1, a2 re-

  shown in Figure 14, since the component according to the

  longitudinal direction of the rails 18 and 19 of the weight of the carriage 14 and parts associated therewith is zero. When the reproduction apparatus is inclined to the right and upwards, as shown in FIG. 15A, the arm 5 is balanced at the points b1 and b2, while the driving force of the linear motor

  28 is balanced with a component Wg sin e of the weight of the chain.

  riot 14 and parts associated with it, according to the direction

  longitudinal direction of the rails 18 and 19. And when the apparatus of

  production is inclined to the left and up, as shown in Figure 153, the arm 5 is balanced at points c1, '2

  when the driving force of the linear motor 28 is balanced

1 9th

20. 6 2460019

  brée with the component of the weight of the carriage 14 and the parts associated therewith in the longitudinal direction of the rails 18

  and 19. Thus, the arm 5 is brought into a state of equilibrium

with one step of slots 82.

  FIG. 16 is a block diagram of a variant of the circuit intended to prevent the free movement of the arm 5. In this diagram, the displacement detector 100 of FIG.

  arms up and down and the electronic switches

  101 and 102 have been removed from the circuit of Figure 12.

  Thus, the circuit of FIG. 16 is simple by comparison

  with that of Figure 12. In accordance with the circuit of FIG.

  re 16, servo-commands to remove the offset angle of the arm 5 and to prevent the free movement of the arm 5, are performed at the same time. In this case, a force exceeding the force corresponding to points d1, d2 ...., e1, e2 .... is

  obtained from the servo system to suppress the angle of

  wedging of the arm 5 (Figure 8). When the two servo-commands are performed simultaneously, the arm 5 is moved step by step in the slots 82. However, when the pitch of the slots 82

  is reduced to 100 lm, and that the displacement control by reaction

  tion is carried out, the stepwise movement of the arm 5 is practically

  out of the question and has no influence on the reproduction

duction of the disc.

  In the reproduction apparatus of this

  tion, as described above, when the arm 5 is moved upwards in the middle of the reproduction of the disk for

  stop this reproduction, the arm 5 is prevented from moving

  freely along the rails 18 and 19. As a result, the arm is stopped in the up position. When in this condition,

  the vertical drive motor 46 is controlled by actuators

  tructions of an actuator, not shown, the arm 5 is moved down and the transducer comes into contact

  with the disc to start playback. When the reproduction

  As the ducting progresses, the arm 5 is moved towards the center of the dis-

  8 along the rails 18 and 19. However, the transducer reaches the innermost groove of the disk 8 to complete the

  reproduction, as indicated by the dashed line in Figure 1.

* The arrival in this position is detected by a detector,

  not shown, the vertical drive motor 46 is again

  calf controlled by the detection of this detector not shown.

  20.- 21.- the arm 5 is moved upwards and then it is driven by the linear motor 28 towards its rest position represented by the lines in dot-dots in the figure la The arm 5 is maintained in its position of rest to be ready for a new reproduction. Although not mentioned in

  the description above, the polarization voltages for

  control the motors 46 and 71 are cut from the amplifiers

  Operator setpoints 91 and 96 during reproduction.

  Although the invention has been described with reference to a particular embodiment, it is obvious to the specialist that modifications can be made to

  this embodiment, without departing from the scope of the invention.

22.-

REVE N D I C A I 0 N S

  1.- Control device for arms in an ap-

  linear displacement reading head apparatus, device comprising guiding means (18, 19), a carriage (14) slidably mounted on said guiding means, a drive motor (28) for driving said carriage in a longitudinal direction of these guide means and a set (5) of read head

  mounted on this truck being able to move and

  carrying a support mechanism (6, 7, 12, 13) for supporting an arm intended to move horizontally with respect to a disc, characterized in that it further comprises means (105, 79, 86, 87) for generating an output signal in response to an inclination of the carriage, and means (106,

  88, 89, 90) for applying this output signal to the motor of

  to stop the truck in a predefined position.

  completed when the arm is away from the disc.

  2. Device according to claim 1, characterized

  in that the means (105) for generating a signal of

  output comprises a light generating element (86), a light source

  light receiver (87) opposed to this generating element

  light, and a plate (79) having an opening (82)

  between the light generating element and the receiving element

  light-generating element, the light generating element and the light-receiving element being mounted on the carriage (14) and the

  plate being mounted on a base member (26, 27).

  3. Device according to claim 1, characterized

  characterized in that the means for detecting the inclination (105, 79, 82, 86, 87) comprises means for generating a sinusoidal output detection signal in response to a movement of the carriage (14), as well as means (106, 88, 89, 90) for

  apply this output signal to the drive motor (28).

  4.- Device according to claim 1, characterized

  characterized in that the drive motor (28) comprises a motor

  linear actuator with a magnetic member (29) arranged parallel-

  along the guide means (18, 19), a

  wearer (31, 35) magnetically coupled with the magnetic member so as to constitute a magnetic circuit and a coil (30) arranged in this magnetic circuit, this coil being fixed

to the carriage (14).

  5.- Device according to claim 4, characterized

23.- 2460019

  characterized in that it further comprises speed detecting means (36) for detecting the speed of movement of the arm (5) in a longitudinal direction of the guiding means (18, 19), said detecting means of the speed comprising a magnetic member (37) arranged parallel along the means of

  guide (18, 19), a yoke member (39, 43) coupled magnetically

  with the magnetic organ so as to constitute a cir-

  magnetic coil and a coil (38) arranged in this magnetic circuit, this coil being fixed to the carriage (14), an output signal then being generated in this coil in response to

  moving the carriage, and means (88, 89, 90) being

  seen to apply this output signal to the linear motor (28)

  so as to prevent undesired movement of the arm (5).

  6. Device according to claim 1, characterized

  characterized in that the read head assembly includes

  detection means (72) for detecting a small quantity of

  horizontal vibration of the arm and to generate an output signal in response to this horizontal vibration, as well as

  means (71) for receiving the output signal thus de-

  riveted by these detection means and to trap this vibration

horizontal in the arm.

  7. Device according to claim 6, characterized

  characterized in that the detection means (72) comprises a

  magnetic member (64), a yoke member (66, 67) coupled

  genetically with this magnetic organ so as to constitute

  a magnetic circuit, and a coil (62) arranged in this circuit.

  magnetic coil, either the coil or the magnetic circuit being fixed to the carriage (14) while the other of these members is fixed to the arm (5) via an arm axis (7), while

  the means (71) for receiving and preventing the horizontal vibration

  Zontale comprises a magnetic member (65), a ram member (66, 68) magnetically coupled with this magnetic member

  to constitute a magnetic circuit, a coil 63)

  in this magnetic circuit, either the coil or the magnetic circuit being fixed to the carriage (14) while the other of these

  bodies is attached to the arm shaft (7).

  8. Device according to claim 7, characterized

  characterized in that the two coils (62, 63) are attached to the arm axis (7) while the two magnetic circuits are fixed

to the carriage (14).

24.- 2460019

  9.- Device according to any one of the

  7 and 8, characterized in that the detection means (72) and the means (71) for receiving and trapping the vibration

  horizontal, are arranged between the guide means, the

  which comprise at least two parallel guide rods (18, 19).

  O-Device according to claim 6, characterized

  in that the read head assembly (5) further comprises means for controlling the arm in a vertical direction

  compared to the disk, these means comprising a drive motor

  (46) for controlling the arm, detecting means (47) for detecting a small amount of vertical vibration of the arm, and for generating an output signal in response thereto.

  vibration, and means (91, 92, 93) for

  this output signal to the drive motor (46) so as to

  to trap the vertical vibration in the arm.

  1lt.- Device according to claim 10, characterized

  characterized in that the drive motor (46) comprises an

  magnet (48), a yoke member (6, 52) coupled magnetically

  with the magnetic organ so as to constitute a cir-

  magnetic coil, and a coil (49) disposed in this magnetic circuit, and the sensor means (47) having an

  magnet (54), a yoke member (6, 58) coupled

  with the magnetic organ so as to constitute a circuit

  magnet and a coil (56) disposed in this magnetic circuit.

  that the coils of the drive motor and the drive means

  being attached to the carriage (14) and the magnetic circuits

being attached to the arm (5).

  12.- Device according to claim 1, characterized

  characterized in that it further comprises detection means

  (103, 74, 76, 77, 78) of an offset angle for detecting the

  arm shift and to generate an output signal in response to the magnitude of this offset angle, a first

  circuit (94) for outputting this output signal to the circuit

  firing the drive motor (88, 89, 90) to control this linear motor to compensate for this offset angle, inclination detecting means (105, 79, 86, 87) being provided to detect an inclination of the carriage (14) and for generating an output signal in response to this inclination of the carriage, a second circuit (106) being provided for applying this output signal derived from the inclination detecting means to the motor control circuit for pocketing an undesirable displacement of the carriage, the first circuit being energized when the arm follows its track on the disk and the second circuit being energized when the arm is moved away from the disk.

  13.- Device according to claim 12,

  characterized in that the first and second circuits comprise

  each a switch (101, 102) which is controlled by a sensor

  arm position sensor, the arm position sensor

  carrying a first member (99) mounted on the carriage (14) and a

  second member (100) mechanically coupled with the arm (5).